Release switch apparatus

ABSTRACT

A release switch apparatus having a release button which is supported in a camera body so as to move between an initial position and a specific operational position in which the release button is pushed down. The apparatus includes a light emitter provided in the release button or in the vicinity thereof and an emission controller for causing the light emitter to emit light when the release button is moved from the initial position. A light receiver is provided in the camera body or in the release button to receive light emitted from the light emitter, and a controller is provided which operates in response to the output to the light receiver.

.Iadd.This application is a continuation of application Ser. No.08/164,438, filed Dec. 9, 1993, now abandoned, which is a ReissueApplication of application Ser. No. 07/620,565, filed Dec. 3, 1990,which issued as U.S. Pat. No. 5,072,248 on Dec. 10, 1991..Iaddend.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a release switch apparatus in which theoperational states of a shutter button of a camera can be visuallyconfirmed, and to a release switch apparatus in which a reaction forceto the operation of the shutter button can easily be optimized.

2. Description of the Related Art

The release switch of a camera is usually of a two-step type in which ashutter button (release button) is pushed down by a half step for afirst operation and by a full step for a second operation, respectively.Specifically, when the shutter button is pushed down by a half step, thephotometering mechanism, the automatic focusing mechanism, and so on areactuated, and when it is pushed down by a full step, a shutter release(exposure) device is actuated. To this end, the conventional shutterbutton has an association member which detects and commences the firstand second operations. The association member, which is, for example, inthe form of a lever for a mechanical shutter or in the form of a contactswitch for an electromagnetic shutter, operates in association with theoperation of the shutter button.

A photographer receives (i.e., feels) different reaction forces whenoperating the release button, depending on whether the half stepoperation or the full step operation is being employed. The photographerrecognizes the half step operation from the reaction thereto.

However, when a picture is taken in cold weather, for example, duringoutdoor photographing in extremely cold regions, or when photographingat a ski resort in winter, the photographers' fingers are often too numbto feel the reaction or, in cases where the photographer is wearinggloves, he or she is unable to feel the reaction. In addition, in caseswhere the camera is attached to a tripod or when a photographer actuatesthe shutter button while looking away from the finder, the photographerhas difficulty in feeling the reaction.

To ensure that the photographer feels the reaction to the half stepoperation, it is possible to increase the reaction force of theassociation member. However, this tends to cause camera shake,particularly in a light camera. Specifically, when the release button ispushed down by a full step, the photographer tends to push the releasebutton down until the push button reaches a lower movement limit, thusresulting in camera shake to a light camera.

To prevent camera shake, it is necessary to reduce the reaction force tothe operation of the shutter button and the reaction force to theoperation of the association member. However, it is very difficult for aphotographer to feel a reduced reaction force. To optimize the reactionforce, it is necessary to adjust the operational forces of variousmechanisms which operate in association with the operation of theassociation member, but this is not technically practicable.

Furthermore, in a conventional camera, it is impossible for the subjectbeing photographed to know when the shutter button is being pushed by ahalf step or by a full step. In particular, with the use of compactcameras, the subject being taken (i.e., photographed) has difficulty inrecognizing the completion of the exposure because the sound made by therelease operation is very small.

SUMMARY OF THE INVENTION

The present disclosure relates to subject matter contained in Japanesepatent applications No. 01-313204 (filed on Dec. 1, 1989) and No.01-313205 (filed on Dec. 1, 1989) and which are expressly incorporatedherein by in their entirety.

The primary object of the present invention is to provide a releaseswitch apparatus in which the operation of the shutter button can beconfirmed visually.

To achieve the object mentioned above, according to the presentinvention, there is provided a release switch apparatus having a releasebutton which is supported in a camera body so as to move between aninitial position and an operational position in which the release buttonis pushed down to a specific position. A light emitter is provided inthe release button or in the vicinity thereof and an emission controlmeans for causing the light emitter to emit light when the releasebutton is moved from the initial position is also provided. A lightreceiver provided in the camera body or the release button to receivelight emitted from the light emitter, and a control mechanism whichoperates in response to the output of the light receiver is provided.

With this arrangement, a photographer can know the operational states ofthe release button when the release button lights up.

Another object of the present invention is to provide a release switchapparatus in which an optimum operational force of the shutter buttoncan be easily obtained.

To achieve this object, the release button is elastically biased to itsinitial position by an elastic member.

Since the reaction force depends only on the elastic biasing force ofthe elastic member, the force necessary for pushing the release buttoncan be easily optimized, depending on the weight of the camera, and soon.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described below in detail with reference to theaccompanying drawings, in which:

FIGS. 1A and 1B are schematic block diagrams of a camera having arelease switch incorporated therein, according to different embodimentsof the present invention;

FIGS. 2, 3, 4 and 5 are schematic views of different embodiments of therelease button according to the present invention;

FIGS. 6A and 6B are schematic views of another embodiment of the releasebutton shown in different operational positions, according to thepresent invention;

FIGS. 7A and 7B are schematic views of still another embodiment of therelease button shown in different operational positions, according tothe present invention;

FIGS. 8A, 8B and 9A and 9B are schematic views of two differentembodiments of the release button shown in different operationalpositions according to the present invention;

FIG. 10 is a schematic view of still another embodiment of the releasebutton according to the present invention;

FIGS. 11A and 11B are timing charts of the operations of the releaseswitch shown in FIG. 5;

FIGS. 12A and 12B are timing charts of the operations of the releaseswitch shown in FIGS. 6A and 6B;

FIG. 13 is a timing chart of the operations of the release switch shownin FIGS. 7A and 7B;

FIG. 14 is a timing chart of the operations of the release switch shownin FIGS. 8A and 8B;

FIG. 15 is a timing chart of the operations of the release switch shownin FIGS. 9A and 9B;

FIGS. 16A, 16B, 16C and 16D are schematic views of different embodimentsof a control circuit for illuminating the release button;

FIG. 17 is a block diagram of a control circuit of an embodiment inwhich a two-color light emitting element is used for the release button;and,

FIG. 18 is a timing chart of the release switch which is made of atwo-color light emitting element.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1A schematically shows a block diagram of the control unit of acamera having a release switch incorporated therein according to thepresent invention.

A release button 1 is supported to move relative to a camera body 15 inthe directions shown by arrows A-B. The release button 1 is continuouslybiased by a return spring 10 in the direction B toward its initialposition in which the release button 1 projects from the camera body 15.When the release button 1 is pushed down in the direction A into thecamera body 15 against the return spring 10, the release operation iseffected. The release button 1 has a light emitter 2 incorporatedtherein. The light emitter 2 is optically connected to a light receiver4 provided in the camera body through a light path 3 which isschematically shown in FIG. 1A. The emission of light of the lightemitter 2 is controlled by an emission controller 9.

The light receiver 4 is connected to a detection signal recognizingdevice 5 which detects when the light receiver 4 receives light from thelight emitter 2 and which is connected to a photometering and focusingcontroller 6 (first control means) which controls the automatic focusingoperation and the photometering operation (optimum exposure valuesetting operation) and a release controller 7 (second control means)which controls the exposure operation.

The detection signal recognizing device 5 detects whether the releasebutton 1 is pushed down by half a step or by a full step in accordancewith the output of the light receiver 4. When the detection signalrecognizing device 5 detects that the release button 1 is pushed down bya half step, the detection signal recognizing device 5 generates acommand signal to the photometering and focusing controller 6. On theother hand, when the detection signal recognizing device 5 detects thatthe release button 1 is pushed down by a full step, the detection signalrecognizing device 5 generates a command signal to the releasecontroller 7.

The photometering and focusing controller 6 operates a photometeringdevice 8a in response to the command signal to meter (or measure) theluminance (or brightness) of a subject to be taken (i.e., photographed)thereby and to set exposure factors (diaphragm value and shutter speed),based on a predetermined algorithm in accordance with the luminance datathus detected, the film sensitivity, and so on. Furthermore, thephotometering and focusing controller 6 operates an automatic focusingdevice 8b to move the focusing lens (not shown) to a focal position inorder to effect the focusing operation.

The release controller 7 operates in response to the command signal toactuate a release device (diaphragm/shutter device) 8c in accordancewith the exposure factors set by the photometering and focusingcontroller 6 in order to carry out the releasing (exposure) operation.

In the illustrated embodiment, although the detection signal recognizingdevice 5, the photometering and focusing controller 6, the releasecontroller 7, and the emission controller 9 are separate devices, thesecan be contained in a single device, for example a microcomputer.

In a modified embodiment shown in FIG. 1B, two light receivers receivingelements 4a and 4b are provided, which will be discussed in more detailhereinafter.

FIGS. 2 and 3 are conceptual views of a first embodiment of a releaseswitch according to the present invention.

In FIG. 2, the release switch has a release button 1, which is supportedin the camera body so as to move between an initial position, a firstposition and a second position, a light emitter 2 and a light receiver4, and an optical path 3b. The optical path 3b is provided in therelease button 1 to optically and selectively connect the light emitter2 and the light receiver 4. The release button 1 is movable in thedirections shown by arrows A-B relative to the camera body. The releasebutton 1 is provided on its lower portion with a coil spring (returnspring) 10 which continuously biases the release button 1 toward theinitial position (direction B). The release button 1 has the opticalpath 3b which is laterally extends through the release button 1. Thecamera body has optical paths 3a and 3c which are positioned opposite tothe ends of the optical path 3b. The other ends of the optical paths 3aand 3c are positioned opposite to the light emitter 2 and the lightreceiver 4, respectively. Consequently, the optical connection betweenthe optical paths 3a, 3b and 3c is broken when the end faces of theoptical path 3b are offset from the associated end faces of the opticalpath 3a and 3c. Conversely, when the release button 1 is pushed down toa predetermined position, the optical connection between the opticalpaths 3a, 3b and 3c is established, so that light emitted from the lightemitter 2 is transmitted to the light receiver 4.

The release button 1 serves also as an optical path by which lightleaked from the portion other than the end faces of the optical path 3bis emitted outward from a pressing surface (top surface) 1a of therelease button 1.

Preferably, the optical paths 3a, 3b and 3c are made of flexible opticalfibers, so that the light emitter 2 and the light receiver 4 can belocated at optional positions.

In a modified embodiment shown in FIG. 3, the light emitter 2 and thelight receiver 4 are provided in the release button 33 and the camerabody 15, respectively. On the side face of the release button 33 a lightemission path 3d is formed which introduces light emitted from the lightemitter 2 to the outside of the camera body 33. The camera body 15 hasanother optical path 3e which optically connects light transmitted fromthe end face of the optical path 3d to the light receiver 4. The opticalpaths 3d and 3e are preferably made of an optical fiber. The releasebutton 33 serves also as an optical path which emits light emitted bythe light emitter 2 from the pressing surface 33a of the release button33.

Since the release button 33 is movable up and down in FIG. 3, the lightemitted from the light emitter 2 can be effectively received by thelight receiver 4 when the end face of the optical path 3d of the releasebutton 33 registers with the end face of the optical path 3e of thecamera body 15.

In a modified arrangement shown in FIG. 4, the release button 34 itselfconstitutes a light emitting element and the release button 34 serves asa light emitting optical path, so that light is emitted from theoperating (pressing) surface 34a of the release button 34. Furthermore,in order to form a light emission optical path (light emission window)3d which introduces the light emitted by the release button 34 into thelight receiver 4 in the camera body 15, the unnecessary peripheralsurface portion of the release switch 34 other than the light emissionwindow is coated with a light intercepting film 12, so that the releasebutton 34 functions similarly to the release button 33 shown in FIG. 3.

The operational force for operating the release switch (FIG. 1A) asconstructed above depends only on the reaction characteristics (springconstant) of the return spring 10; thus, an optimum operational force ofthe release switch can be easily obtained.

The release button 34 is movably supported in a button guide hole 15aformed in the camera body 15 and a escaping hole 15b connected to thebutton guide hole 15a. The release button 34 has at its lower end aflange portion 34b integral therewith which restricts the initialposition in which the flange portion 34b comes into contact with astepped stop (shoulder portion) 15d which is formed between the buttonguide hole 15a and the escaping hole 15b. If the release button 34 iscylindrical, a key and key way are provided on the release button 34 andthe camera body 15 to prevent the release button from rotating. Such arotation preventing means (e.g. key and key way) is unnecessary if therelease button has a non-circular cross sectional shape (e.g. ellipticalor polygonal shape). This can be applied to all of the embodimentsmentioned above and those that will be described below.

FIG. 5 shows another embodiment of the release switch 35 which isbasically similar to the release switch shown in FIG. 4 except for thefollowing features. Namely, in FIG. 5, the stepped stop 15d has anelectrical contact 20a which comes into contact with an electricalcontact 20b provided on the upper surface of the flange portion 35b ofthe release switch 35 at the initial position. Furthermore, the lightemission window (light emitting path) 3d which is defined by the lightintercepting film 12 is elongated in the direction of the movement ofthe release button 35. Light emitted from the release button 35 isemitted from the operating surface (pressing surface) 35a of the releasebutton 35.

The release button 35 is normally maintained in the initial position bythe coil spring 10, so that the contacts 20a and 20b are in contact witheach other. When the release button 35 is pushed down by a half step,the release button 35 comes to a half step position (intermediateposition) in which the contact 20b separates from the contact 20a, asshown in FIG. 5. In this intermediate position, the release button 35emits light which is received by the light receiver 4. The output signalof the light receiver 4 is input to the detection signal recognizingdevice 5 (FIG. 1A) which issues and sends a command signal in responseto the detection signal to the photometering and focusing controller 6.As a result, the photometering and focusing controller 6 causes thephotometering device 8a and the automatic focusing device 8b to set theexposure value and perform the focusing, respectively.

When the release button 35 is further pushed down by a full step, thelight emitting optical path 3d is offset from the light entrance path3e, so that the optical connection there between is broken. As a result,the light receiver 4 no longer receives light from the release button35. This is detected by the detection signal recognizing device 5 whichsends the command signal to the release controller 7 which in turncauses the release device 8c to perform the exposure operation. Uponcompletion of the exposure operation, the emission controller 9 causesthe light emitter 2 to stop the emission.

When a photographer's finger is released from the release button 35, thelatter is moved upward to project from the camera body by the coilspring 10, so that the contact 20b comes into contact with the contact20a again. Consequently, the detection signal recognizing device 5 andso on are reset and returned to the initial position. The emissioncontroller 9 stops the emission. Alternatively, it is possible for theemission controller 9 to stop the emission when the release controller 7outputs the shutter operation signal.

FIGS. 16A˜16D show different examples of a control circuit for lightingup the release button 35 upon the separation of the contacts 20a and20b, and will be described below.

FIGS. 11A and 11B show timing charts of the above-mentioned operations.

Note that it is possible to make the release button 35 of a lightreceiving element, wherein the light receiver 4 in the camera body isreplaced with a light emitter to perform the same function as mentionedabove.

If a two-color light emitter is used, it is possible to change the colorwhen the exposure is effected or during the exposure in order to let aphotographer or a third person visually confirm the state of the shutterrelease operation. Such a color indication is particularly useful duringa self-timed photograph using a tripod or when a photographer pushes theshutter button while looking away from the finder.

In the release switch shown in FIGS. 6A and 6B, the release button 36 iscoated with the light intercepting film 12 which forms first and secondlight emission windows (optical paths) 3d and 3f, spaced from oneanother in the direction of the movement of the release switch 36. Thecamera body 15 has first and second incident paths (incident windows) 3eand 3g corresponding to the first and second optical paths 3d and 3f.The incident paths 3e and 3g are connected to a common light receiver 4.

Alternatively, it is possible to provide two independent light receivers4 corresponding to the incident paths 3e and 3g, respectively. Lightemitted from the release button 36 is also emitted from the operatingsurface (pressing surface) 36a.

In the release switch shown in FIGS. 6A and 6B, when the release button36 is pushed down by a photographer, the contact 20b separates from thecontact 20a, so that the release button 36 emits light, as shown in FIG.6A. When the release button 36 is further pushed down to a firstposition in which the second emission path 3f of the release button 36is substantially registered with the first incident path 3e of thecamera body 15 (FIG. 6A), the light receiver 4 receives light emittedfrom the release button 36. The receipt of the light is detected by thedetection signal recognizing device 5 (FIG. 1A), so that thephotometering and focusing controller 6 causes the photometering device8a and the automatic focusing device 7 to set the exposure value andeffect the focusing, respectively.

A further downward movement of the release button 36 to a secondposition in which the first and second optical paths 3d and 3f of therelease button 36 are substantially registered with the correspondingfirst and second optical paths 3e and 3g of the camera body 15,respectively, causes the light receiver 4 to receive a higher intensityof light emitted from the release button 36 than at the first positionshown in FIG. 6A, as shown in FIG. 6B. This is detected by the detectionsignal recognizing device 5, so that the shutter release operation iscarried out by the release device 8c through the release controller 7(FIG. 1B).

In order to perform the above-mentioned control by digitally changingthe level (intensity or quantity) of light received by the lightreceiver 4, it goes without saying that the detection signal recognizingdevice 5 must be capable of detecting such a digital change in lightintensity.

In the case where two light receivers 4 are provided corresponding tothe optical paths 3e and 3g, the detection signal recognizing device 5is constructed in such a way that the focusing operation and theexposure value setting operation are performed when one of the lightreceivers detects a predetermined quantity of light, and the releaseoperation is performed when both the light receivers 4 detect apredetermined quantity of light. These operations are shown in a timingchart of FIG. 12A.

FIG. 12B shows a timing chart of the operations when the light receiverconsists of two light receivers. In FIG. 12B, the first operation(focusing and photometering, etc.) is performed when the first lightreceiver receives a predetermined quantity of light and the firstoperation is stopped when the first light receiver does not receive apredetermined quantity of light. Thereafter, the exposure operation(second operation) is performed when both the first and second lightreceivers receive a predetermined quantity of light. Upon completion ofthe exposure, the emission of light of the light emitter is stopped.After that, when the contacts 20a and 20b are closed (i.e. contactedwith each other), the light emitter is reset.

The release switch shown in FIGS. 7A and 7B is basically similar to therelease switch shown in FIGS. 6A and 6B, except for the provision offilters on the optical paths 3d and 3f. Namely, the first and secondoptical paths 3d and 3f of the release button 37 are coated withrespective filters f1, f2 having different light transmissionefficiencies or light reflection efficiencies, so that differentquantities of light or different wavelengths of light can be transmittedthrough the filters. Furthermore, only one incident path 3e is providedin the camera body 15 in the arrangement shown in FIGS. 7A and 7B.

The quantity (or intensity) of light which is received by the lightreceiver 4 when the second optical path (emission path) 3f is registeredwith the optical path (incident path) 3e, that is, when the releasebutton 37 is pushed down by a half step as shown in FIG. 7A, isdifferent from the quantity (or intensity) of light which is received bythe light receiver 3 when the first optical path (emission path) 3d isregistered with the optical path (incident path) 3e, that is, when therelease button 37 is pushed down by a full step, as shown in FIG. 7B,due to the presence of the filters having different light transmissionefficiencies. The detection signal recognizing device 5 detects thedigital change in quantity (or intensity) of light received by the lightreceiver 4 to control the focusing operation and the setting operationof the exposure value to control the exposure operation. Note that lightis emitted also from the operating surface (pressing surface) 37a of therelease button 37. It is possible to use a light receiver in which thesensitivity varies depending on the wavelength of light received therebyto simplify the discrimination of the output levels thereof.

The operations of the release switch shown in FIGS. 7A and 7B is shownin the timing chart shown in FIG. 13. In the timing chart, the intensityof light output from the second emission path 3f is smaller than thatoutput from the first emission path 3d. Conversely, if the intensity oflight output from the second emission path 3f is higher than that outputfrom the first emission path 3d, the arrangement of wave shapes isreversed.

A release switch 38 shown in FIGS. 8A and 8B is slightly different fromthe release switch shown in FIGS. 6A and 6B in the arrangement of theoptical paths 3d and 3f. Namely, in FIGS. 8A and 8B, the first andsecond optical paths (emission paths) 3d and 3f are circumferentiallyspaced from one another on the periphery of the release button 38. Thefirst and second incident paths 3e and 3g are provided in the camerabody 15 so as to be opposed to the respective optical paths (emissionpaths) 3d and 3f, respectively. The incident paths 3e and 3g areconnected to the respective light receivers 4a and 4b. Light is emittedfrom the operating surface 38a of the release button 38.

When the release button 38 is pushed down by a half step, as shown inFIG. 8A, the second emission path 3f is registered with the secondincident path 3g, so that the second light receiver 4b receives lightfrom the emission path 3f. This is detected by the detection signalrecognizing device 5, so that the photometering and focusing controller6 causes the photometering device 8a and the automatic focusing device8b to set the exposure value and effect the focusing operation,respectively.

When the release button 38 is pushed down to the second position by afull step, as shown in FIG. 8B, the first emission path 3d is registeredwith the first incident path 3e, so that the first light receiver 4areceives light emitted from the light emitter 2 through the firstemission path 3d. The receipt of light of the first light receiver 4a isdetected by the detection signal recognizing device 5, so that therelease controller 7 causes the release device 8c to effect theexposure. The operations mentioned above are as shown in the timingchart of FIG. 14.

A release switch shown in FIGS. 9A and 9B is basically similar to therelease switch shown in FIG. 5 except for an elongated emission path 3dwhich is provided in the release button 39 to extend in the direction ofthe movement of the release button 39 and a wide optical path (incidentpath). 3e connected to the light receiver 4 which can detect both thehalf step operation and full step operation of the release button 39.Light is emitted from the operating surface 39a of the release button39.

The release switch 39 operates as follows.

When the release button 39 is pushed down by a half step, as shown inFIG. 9A, the contact 20b separates from the contact 20a, so that therelease button 39 emits light. A further downward movement of therelease button 39 increases the sectional area of the registration ofthe emission path 3d of the release button 39 with the incident path 3eof the camera body 15. The increased sectional area of registrationincreases the intensity (level) of light received by the light receiver4.

The intensity of light received by the light receiver 4 is detected bythe detection signal recognizing device 5 which judges the half stepoperation when the intensity of light is above a first predeterminedvalue. As a result, the detection signal recognizing device 5 sends thecommand signal to the photometering and focusing controller 6 whichcauses the photometering device 8a and the automatic focusing device 8bto set the exposure value and effect the focusing operation,respectively.

When the release button 39 is pushed down by a full step, as shown inFIG. 9B, the intensity of light is above a second predetermined value.As a result, the detection signal recognizing device 5 sends the commandsignal to the release controller 7 which causes the release device 8c toeffect the release operation.

To perform the control mentioned above in accordance with the intensityof light which analogically varies, the detection signal recognizingdevice 5 must function to detect the analogical change of the intensityof light.

The operation of the release switch 39 is as shown in a timing chart ofFIG. 15.

The release switch shown in FIG. 10 is basically similar to the releaseswitch shown in FIG. 4, except for two emission paths 3d and 3f whichare provided in the release button 40, itself comprised of a two-colorlight emission element, and spaced from one another in the direction ofthe movement of the release button 40. The first and second emissionpaths 3d and 3f have first and second filters f3, f4 attached thereto,which permit the first and the second colors of light to passtherethrough and do not permit the second and first colors of light topass there through, respectively.

FIG. 17 shows a block diagram of a control unit of the embodiment shownin FIG. 10. In the control unit shown in FIG. 17, the color of light tobe emitted from the light emitter 2 is varied by the emission controller9 in accordance with the output of the photometering and focusingcontroller 6, unlike the embodiment shown in FIG. 1A. In the embodimentillustrated in FIG. 17, the first filter of the first optical path 3dpermits a first color of light to pass therethrough but does not permita second color of light to pass, and the second filter of the secondoptical path 3f permits the second color of light to pass therethroughbut does not permit the first color of light to pass, respectively.

When the release button 40 is pushed down a half step by thephotographer, the contact 20b separates from the contact 20a so that therelease button 40 emits the first color of light. When the releasebutton 40 is further pushed down, the first emission path 3d isregistered with the incident path 3e. As a result of this, the lightreceiver 4 receives the first color of light from the release button 40,since the first filter of the first emission path 3d permits the firstcolor of light to pass therethrough. As a result, the light receiver 4sends a detection signal to the detection signal recognizing device 5which sends the command signal to the photometering and focusingcontroller 6. Consequently, the latter causes the photometering device8a and the automatic focusing device 8b to set the exposure value andeffect the focusing operation, respectively. At this moment, theemission controller 9 causes the release button 40 to emit the secondcolor of light.

When the release button 40 is pushed down by a full step, the secondemission path 3f is registered with the incident path 3e. As a result,the light receiver 4 receives the second color of light emitted from therelease button 40, since the second filter of the second emission path3f permits only the second color of light to pass therethrough. As aresult, the light receiver 4 sends a detection signal to the detectionsignal recognizing device 5 which sends the command signal to therelease controller 7. Consequently, the latter performs the exposureoperation.

When the external force by the photographer is released from the releasebutton 40, the release button 40 is returned to the initial position bythe return spring 10 to project from the camera body. During the returnmovement, when the optical connection of the second emission path 3f andthe incident path 3e is broken, the release button 40 changes the colorof light to be emitted therefrom to the first color of light. Theabove-mentioned operations are as shown in a timing chart of FIG. 18.

FIGS. 16A-16D show different examples of a control circuit forilluminating the release button 35 upon the separation of the contacts20a and 20b.

FIG. 16A shows a semiconductor control circuit for a light emittingelement 50, forming part of the release button 1 and 33-40. An anode endof emitter 50 and one end of a resistor R₁ are connected to +V. Acathode end of the emitter 50 is connected to the collector of NPNtransistor Tr1. A second end of the resistor R₁ is connected to the baseof transistor Tr1 and contact 20a. One end of resistor R₂ is connectedto the emitter of Tr1. A second end of resistor R₂ and contact 20b areconnected to ground. Separation of contacts 20a, 20b controlsillumination of emitter element 50.

FIG. 16B discloses a similar control circuit constructed to utilize aPNP transistor Tr2. The operation is substantially the same as for thecircuit illustrated in FIG. 16a.

FIG. 16C illustrates a control circuit wherein one end of a currentlimiting resistor is connected to the anode of emitter 50. The cathodeof emitter 50 is connected to ground. The selective opening of contacts20a and 20b causes the emitter to emit light.

FIG. 16D discloses a microcomputer and driving circuit to which emitter50 is connected to be selectively driven in response to opening andclosing of switch 20. It is known in the art how to construct electronicdriving circuits in which the emitter 50 emits light using eithernormally open or normally closed switches for contacts 20a, 20b.

As can be seen from the foregoing, in the illustrated embodiments, sincethe release button emits light in accordance with the half stepoperation thereof, the full step operation, and the commencement of therelease operation, the state of the release button can be visuallyconfirmed.

According to the present invention, since the release button 34˜40itself is made of a mold of light emitting material, the assembly of therelease switch can be easily and inexpensively effected.

The shape and size of the release button are not limited to those in theillustrated embodiments, but preferably are such that the release buttonis not completely covered with an operator's finger when the releasebutton is actuated thereby, to ensure that the release button can be atleast partially observed.

Furthermore, according to the present invention, since neither thecontact nor the lever are pressed during the downward movement of therelease button, a substantially constant pressing force which dependsonly on the spring force of the coil spring 10 can be applied to therelease button. The coil spring 10 can be replaced with a leaf spring,sponge or rubber, etc.

Although the light emitter and the light receiver(s) are provided on therelease button and the camera body respectively in the illustratedembodiments, it is possible to provide the light emitter and the lightreceiver(s) on the camera body and the release button, respectively.

In the present invention, it is also possible to make the conventionalrelease button of a light emitting element.

As can be seen from the above discussion, according to the presentinvention, since the release button emits light in accordance with theoperational state of the release button, a photographer can visuallyconfirm and adjust the position of the release button.

If the whole release button is made of a light emitting material, therelease switch is simplified and can be easily and inexpensivelyassembled.

I claim:
 1. A release switch apparatus .[.having.]. .Iadd.for a camera,comprising:.Iaddend.a release button which is supported in a camera bodyso as to move in a predetermined direction between an initial positionand a specific operational position in which said release button ispushed down.[., comprising:.]..Iadd.;.Iaddend. a light emitter providedin .[.one of said release button or.]. said camera body .Iadd.andmovable in association with movement of said release button when saidrelease button is pushed down towards said specific operationalposition.Iaddend.; emission control means for causing said light emitterto emit light when said release button is moved from said initialposition; a light receiver which is provided in .[.the other one of.].said camera body .[.or said release button.]. to receive light emittedfrom said light emitter; and.[.,.]. control means which operates inresponse to the output of said light receiver.Iadd.; wherein saidrelease button has an operational surface which is pressed by anoperator and a light emission path, which emits light, emitted by thelight emitter, from said operational surface.Iaddend.. .[.2. A releaseswitch apparatus according to claim 1, wherein said release button hasan operational surface which is pressed by an operator..]..[.3. Arelease switch apparatus according to claim 2, wherein said releasebutton has a light emission path which emits light, emitted by the lightemitter, from said operational surface..].4. A release switch apparatusaccording to claim .[.3.]. .Iadd.1.Iaddend., further comprising biasingmeans for continuously biasing said release button to the initialposition.
 5. A release switch apparatus according to claim .[.3.]..Iadd.1.Iaddend., fiber comprising electrical contact means fordetecting the movement of said release button from said initialposition.
 6. A release switch apparatus according to claim 5, whereinsaid electrical contact means comprises electrical contacts which areprovided on said camera body and said release button to come intocontact with and separate from each other when said release button is insaid initial position and when said release button is moved from saidinitial position.
 7. A release switch apparatus according to claim 6,wherein said emission control means causes said light emitter to emitlight when said electrical contacts separate from one another.
 8. Arelease switch apparatus according to claim 1, wherein said controlmeans comprises a first control means for metering luminance of anobject to be taken to set an exposure factor.
 9. A release switchapparatus according to claim 8, wherein said first control meanscomprises means for automatic focus control of a lens.
 10. A releaseswitch apparatus according to claim 1, wherein said control meanscomprises a second control means for performing an exposure operation.11. A release switch apparatus according to claim 1, wherein said lightemitter is incorporated in said release button to be integral with saidrelease button.
 12. A release switch apparatus .[.according to claim1,.]. .Iadd.for a camera comprising:a release button which is supportedin a camera body so as to move in a predetermined direction between aninitial position and a specific operational position in which saidrelease button is pushed down; a light emitter provided in said camerabody and movable in association with movement of said release buttonwhen said release button is pushed down towards said specificoperational position; emission control means for causing said lightemitter to emit light when said release button is moved from saidinitial position; a light receiver which is provided in said camera bodyto receive light emitted from said light emitter; and control meanswhich operates in response to the output of said lightreceiver;.Iaddend. wherein said release button has a light emission paththrough which light emitted by said light emitter is emitted in apredetermined direction. A release switch apparatus according to claim12, wherein said light emission path is an elongated path extending inthe direction of the movement of said release button.
 14. A releaseswitch apparatus according to claim 13, wherein said camera body has alight incident path which is optically connected to said light emissionpath when said release button is moved to an intermediate positionbetween said initial position and said specific operational position andwhich is optically disconnected from said light emission path when saidrelease button is moved to said specific operational position.
 15. Arelease switch apparatus according to claim 12, wherein said lightemission path has first and second optical paths which are spaced fromone another in the direction of the movement of .[.the.]. .Iadd.said.Iaddend.release button.
 16. A release switch apparatus according toclaim 15, wherein said camera body has a first incident path which isoptically connected to said second optical path of said release buttonwhen said release button is moved to an intermediate position betweensaid initial position and said specific operational position, and asecond incident path which is optically connected to said second opticalpath when said release button is moved to said specific operationalposition.
 17. A release switch apparatus according to claim 16, whereinsaid first and second incident paths are optically connected to saidfirst and second optical paths when said release button is in saidspecific operational position, respectively.
 18. A release switchapparatus according to claim 17, further comprising a detection signalrecognizing means for discriminating the output signals of said lightreceiver, and wherein said control means comprises at least first andsecond control means for performing different control operations, sothat said detection signal recognizing means operates said first andsecond control means in accordance with the discrimination signal ofsaid detection signal recognizing means.
 19. A release switch apparatusaccording to claim 15, wherein said camera body has one incident pathwhich is optically connected only to said second optical path of saidrelease button when said release button is moved to an intermediateposition between said initial position and said specific operationalposition and which is optically connected only to said first opticalpath when said release button is moved to said specific operationalposition. . A release switch apparatus according to claim 19, whereinsaid first and second optical paths are provided with optical filtershaving different light transmission efficiencies.
 21. A release switchapparatus according to claim 20, further comprising a detection signalrecognizing means for discriminating the output signals of said lightreceiver, and wherein said control means comprises at least first andsecond control means for performing different control operations, sothat said detection signal recognizing means operates said first andsecond control means in accordance with the discrimination signal ofsaid detection signal recognizing means.
 22. A release switch apparatusaccording to claim 19, wherein said first and second optical paths areprovided with optical filters which permit different wavelengths oflights to pass therethrough, respectively.
 23. A release switchapparatus according to claim 22, further comprising a detection signalrecognizing means for discriminating the output signals of said lightreceiver, and wherein said control means comprises at least first andsecond control means for performing different control operations, sothat said detection signal recognizing means operates said first andsecond control means in accordance with the discrimination signal ofsaid detection signal recognizing means.
 24. A release switch apparatusaccording to claim 19, wherein said light emitter comprises a two-colorlight emitting element.
 25. A release switch apparatus according toclaim 24, wherein said emission control means varies the color of lightemitted from said light emitter within a predetermined range on thedirection of the movement of said release button.
 26. A release switchapparatus according to claim 25, wherein said emission control meanscauses said light emitter to emit a first color of light and a secondcolor of light when said release button is moved from said initialposition and when said second optical path is registered with saidsecond incident path, respectively.
 27. A release switch apparatusaccording to claim 26, wherein said first optical path is provided withan optical filter which permits said second color of light to passtherethrough and does not permit said first color of light to passtherethrough.
 28. A release switch apparatus according to claim 27,wherein said second optical path is provided with an optical filterwhich permits said first color of light to pass therethrough and doesnot permit said second color of light to pass therethrough.
 29. Arelease switch apparatus according to claim 26, wherein said emissioncontrol means causes said light emitter to emit said first color oflight when said light receiver no longer receives said second color oflight after said light emitter emits said second color of light.
 30. Arelease switch apparatus according to claim 12, wherein said lightemmision path has first and second optical paths which arecircumferentially spaced from one another about said release button. 31.A release switch apparatus according to claim 30, wherein said camerahas a second incident path which is optically connected to said secondoptical path of said release button when said release button is moved toan intermediate position between said initial position and said specificoperational position, and a first incident path which is opticallyconnected to the said fist optical path when said release button ismoved to said specific operational position.
 32. A release switchapparatus according to claim 31, wherein said first incident path is notoptically connected to said first optical path when said release buttonis in said intermediate position, and said second incident path is notoptically connected to said second optical path when said release buttonis in said specific operational position.
 33. A release switch apparatusaccording to claim 32, further comprising a detection signal recognizingmeans for discriminating the output signals of said light receivers, andwherein said control means comprises at least first and second controlmeans for performing different control operations, so that saiddetection signal recognizing means operates said first and secondcontrol means in accordance with the discrimination signal of saiddetection signal recognizing means.
 34. A release switch apparatus.[.having.]. .Iadd.for a camera, comprising:.Iaddend.a release buttonwhich .Iadd.is .Iaddend.supported in a camera body so as to move betweenan initial position and an operational position in which said releasebutton is pushed down to a specific position.[.,comprising:.]..Iadd.;.Iaddend. a light emitter which is provided in.[.one of said release button or.]. said camera body; emission controlmeans for causing said light emitter to emit light when said releasebutton is moved from said initial position; a light receiver which isprovided in .[.the other one of.]. said camera body .[.or said releasebutton.]. to receive light emitted from said light emitter; and controlmeans which operates in response to the output of said light receiver;said release button being provided with an optical path which breaks andestablishes an optical connection of said light emitter and said lightreceiver at said initial position and said specific position,respectively. .Iadd.35. The release switch apparatus according to claim1, said release button comprising said light emitter..Iaddend..Iadd.36.The release switch apparatus according to claim 1, positioning of saidrelease button spaced from said initial position along a directiontowards said specific operational position interrupting a light pathbetween said light emitter and said light receiver..Iaddend.